The present invention relates to heat exchanger systems for use generally with electronic applications. More particularly, the present invention relates to heat exchanger bodies having oriented micro-scale channels and methods of fabricating such bodies.
Rapid advances in large-scale integrated electronics packaging, lightweight composite structures, and high conductivity materials are enabling the development of new manufacturing and integration technology called multifunctional structures (“MFS”). The main MFS concept is to embed electronics assemblies (e.g., multi-chip modules, or “MCM”), integral thermal management, miniature sensors, and actuators into load carrying structures along with associated embedded cabling for power and data transmission. This integration yields major weight, volume and cost savings. While MCMs offer considerable reduction in both the microelectric packaging volume and interconnection signal delay, the integration results in higher heat fluxes. Thus, thermal management of microelectronic devices is required to provide suitable heat dissipation for proper operation and acceptable reliability. The methods of connecting the signals and power from the MCM to the next level package (e.g., printed wiring board or 3-D MCM stack) presents heat removal challenges.
Improved cooling techniques are required for reliable electronics given current trends toward increased packaging densities and higher power levels, especially in fields like aircraft avionics, electric power systems, radar and weapons systems. Further confounding thermal management of aircraft electronics is a limited availability of compatible heat sink coolants at suitable temperatures. Very high heat fluxes (500 to 2000 W/cm2) must be cooled in Directed Energy Weapon (“DEW”) systems, including High Energy Laser (“HEL”) diodes and High Power Microwave (“HPM”) Gyrotrons and Klystrinos. Closed and open look (expendable) cooling systems are being developed to handle transient heat loads as large as 1 MW. Cost, reliability, weight, and volume are key factors in designing cooling systems for both power conversion and weapons systems. The required flow rates and temperature level of the coolant are both significant. Therefore, compact cooling approaches that are capable of handling the high heat fluxes at a low thermal resistance are needed. Compact cooling systems are also needed in cellular and radio communications equipment, air traffic control and monitoring systems, and high-powered amplifiers.
One type of cooling system incorporates a microchannel heat sink. The heat sink can be made from a thermally conductive solid, typically copper or silicon, with a single layer of small channels fabricated into the surface of a structure. The channels are fabricated by precision machining or chemical etching. Thus, the machining or etching capabilities will limit the size, number and configuration of the channels that can be fabricated on the surface of the structure. The need for secondary bonding processes to fabricate a heat sink also presents challenges.
Another method of compact cooling involves an integrated die substrate and cooler concept to provide high-performance heat sinking for high power dissipation devices. The cooler is a bonded stack of identical laminations, with every other lamination in the stack flipped to provide an axis-symmetric mating lamination. The pattern is designed to that the rounded slot-ends of a flipped lamination overlap the slot-ends of the un-flipped lamination. Essentially, a circular portal is created connecting slots of adjacent layers in the stack. While this concept is efficient, it is a very complicated structure to fabricate and therefore expensive.
Therefore, there remains a need for compact heat exchanger systems for electronic and other applications that can be manufactured in an efficient and cost-effective manner.